Which element is a halogen?
argon
bromine
calcium
lithium
The Correct Answer and Explanation is :
The correct answer is bromine.
Bromine is classified as a halogen, which is a group of elements found in Group 17 (formerly Group VIIA) of the periodic table. The halogens include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). These elements share similar chemical properties, primarily due to their valence electron configuration, which has seven electrons in their outer shell. This makes them highly reactive, as they tend to gain one electron to achieve a stable octet configuration.
Bromine is unique among the halogens because it is the only one that is a liquid at room temperature. It has a reddish-brown color and emits a strong, unpleasant odor. Like other halogens, bromine readily forms compounds with metals and nonmetals. For example, it reacts with sodium to form sodium bromide (NaBr), a common salt. Bromine is also used in various industrial applications, including flame retardants, pharmaceuticals, and certain types of photography.
In contrast, argon is a noble gas found in Group 18 of the periodic table and is known for its lack of reactivity due to having a full valence shell of eight electrons. Calcium (Ca) is an alkaline earth metal located in Group 2, and lithium (Li) is an alkali metal in Group 1. These elements do not possess the characteristic properties of halogens.
The reactivity of bromine, as with other halogens, decreases as you move down the group. For example, iodine is less reactive than bromine, while fluorine is the most reactive halogen. Understanding the properties of halogens like bromine is essential in various fields, including chemistry, materials science, and environmental studies, due to their significant role in forming diverse chemical compounds.